def func1():
    x = 50
    y = x ** 0.5 - 7
    print(y)

def func2():
    x = 70
    y = x ** 0.5 - 7
    print(y)
    return y

def func3(x):
    y = x ** 0.5 - 7
    return y

def func4(x=50):
    y = x ** 0.5 - 7
    return y

def calculate(a, b, operation="add"):
    if operation == "add":
        return a + b
    elif operation == "subtract":
        return a - b
    else:
        return None


def func6(a, b, operation="add"):
    if operation == "add":
        return a + b
    elif operation == "subtract":
        return a - b
    else:
        return None

def func7(a, b, operation="add"):
    if operation == "add":
        return a + b
    elif operation == "subtract":
        return a - b
    else:
        return None

def func8(numbers):
    total = 0
    for num in numbers:
        total = total + num
    return total

